Installing the Suspension Upgrade

by Hank Barta

As of January, 2002 Elsie is all mine. I decided that it was time to upgrade the suspension. At 54K miles, the factory shocks had done their job and by most accounts, were no longer providing good damping. I decided that instead of replacing them with something that matched factory performance, I would up the ante. I studied the various options available and decided on the Flyin Miata (FM) package that included KYB AGX shocks, FM springs, front and rear FM sway bars and the FM shock tower brace. My concern was that the package be balanced - that the performance of all of the parts would match. FM has a good reputation in the market so I hoped that their package would be well matched.

The installation

There is a lot of good information on so I won't bother repeating that here. I chose the 'split at the ball joint' method and will only add that whoever pushes down on the upper A-arm should wear leather gloves. I sliced open my palm on a sharp burr before I figured this out. :-(

My main contribution to the shared body of knowledge is what to do regarding bump stops and boots. With the lowered springs, the bump stops need to be modified to retain clearance and reasonable suspension travel. There is some very detailed information on this at Jyri Virkki's site. I more or less followed the guidelines provided by FM and provided modifications to install aftermarket shock boots. I used red boots from Summit Racing, part number RAN-RS1927. The boots cost $6.95US. Since the existing boots were deteriorated to the point of splitting when I pulled them off, I thought these were worth a try. Factory boots cost about $20, and they include new bump stops that I would wind up cutting up anyway.
front springs and shocks, 36K

Here's what the old and new parts look like, front on the left and rear to the right. (Click on these and other images to see the full size.)

rear shocks and springs, 28K
front bump stop and boot., 29K

This is the front bump stop. I used snips to cut off the boot and outer edge of the lowest 'bumper.' My intent was to make it small enough to slip in to the boot, but not too easily. In fact, I had to lubricate it with liquid dish detergent and cut the small tits off the bottom of the bumper to slide the boot over the bottom of the bumper. It looks like it should be pretty secure. I left the zip tie off because I thought it would pop the first time I compressed the bump stop.

boot fitted to front bumper, 28K

The replacement boot itself was longer than the stock boot. The shock had a collar on which a boot could be fastened. This can be seen in the picture above about an inch from the spring support. Since the boot was longer, I simply slipped the boot over this ring. The whole assembly looks pretty attractive. I'm afraid that the images don't really do it justice. ;)

front assembly, 34K
unmodified rear bumper, 21K modified rear bumper, 24K

The rear bump stop required additional modification. FM recommended that the 'middle donut' be removed. They also said that the boot could be left on or removed as desired. In fact, the top of the boot also includes part of the bump stop as can be seen on the cut away portion of the front bump stops. I needed to reduce the height but still leave something to hold the boot. I hacked off the boot+bumper leaving the donut (that should be removed according to FM.) To reduce the effective height, I took a die grinder with a small sanding drum and ground away at the inside of the donut, tapering it out to the outer edge. That reduced the stack height beyond the reduction realized by removing the boot and its attached bumper. That still left the outside of the donut over which I slid the boot.

rear boot installed on bump stop, 21K

The rear bump stop showing the boot installed. Again, getting this on required using a liquid dish detergent and a bit of muscle. The top of the boot slipped into the groove above donut and appears pretty secure.

On the rear assembly I slipped the boot over the boot flange on the rear shock as I had done on the front.

rear assembly, 36K
rear boot installed on bump stop, 52K

This is the final result. Too bad these black and red babies are hidden behind the wheels. You can also see the ends of the sway bars in these pictures.

rear assembly, 49K

The results

I installed this in stages because I was waiting for the spring compressor that was back ordered from Harbor Freight. The shock tower brace went in first. I don't know if I can really tell the difference. The next part was the sway bars. They really flattened the car in the curves. They added a little harshness otherwise due to the coupling of both sides of the car. Overall, I believe that the sway bars would be a worthwhile upgrade by themselves if you wanted to reduce body roll. Then I added the springs and shocks. They lowered the car and really firmed up the suspension. At present I have the shocks set to 3 all around. I haven't really spent any time fooling around with different settings. I've done some around town driving and one 200 mile club tour. The ride "sure is firm" but not something I find objectionable. I haven't tried it on the autocross course, so I don't really know if the handling is improved. Yet. We have an event scheduled shortly. :) :) :)


As with all other projects I've completed on our Elsie, I researched this through, the Miata Forum, and the Web before I struck out on my own. My success in these endeavors is largely a result of what others have tried before me and taken the time to write about so others like myself may benefit. I am grateful to those who have contributed to our body of Miata knowledge and hope that my web pages add their own small contribution.

Copyright 2002 all rights reserved

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31 May, 2002